Why does one need two RCA cables (i.e. red and white) to plug into a mono channel subwoofer amplifier? It seems to play just fine with only one "channel" plugged in... Why is the subwoofer output "left and right"? Thanks for answering my stupid question.

Still curious.

You don't if you have a true mono out on your headunit.

Some headunit's "subwoofer" outputs double as a "non-fading" output ,which would be stereo.

Being a recording "engineer" during mixdown bass information is held within the stereo spectrum in both left and right channels. Example a chorused bass is actually two different bass frequencies panned in the spectrum and if your only using one side your missing the other side, also double kick are sometimes panned apart and guitars are often panned left and right. So if you are not running your bass in stereo they must be summed in mono at your head unit or your amplifier. Without this action being performed your actually only hearing half or one side of the spectrum resulting in bass loss. This is the reason engineers always will have subs in stereo for mixdown unless they are mixing down to 5.1 and that's typical for cinema only, not "car audio"

Edited January 1, 201114 yr by Cant Get Enough